1. Field of the Invention
The present invention relates to a portable apparatus and, more particularly, to an apparatus using a battery and a method of detecting a time to change/recharge the battery of the apparatus.
2. Description of Related Art
Conventional portable apparatuses employ a battery as a power source and include a circuit for detecting a battery voltage in order to inform a user of the time to change or recharge the battery.
FIG. 1 is a block diagram of a conventional apparatus using a battery.
Referring to FIG. 1, the apparatus includes a battery 10, a function unit 12, a reference voltage generator 14, a voltage divider 16, a comparator 18, and a controller 20. The voltage divider 16 includes resistors R1 and R2. In FIG. 1, the reference voltage generator 14, the voltage divider 16, and the comparator 18 constitute a battery voltage sensor.
Functions of the respective blocks shown in FIG. 1 will now be described.
The battery 10 supplies a battery voltage VBB. The function unit 12 receives the battery voltage VBB and performs its own operation under the control of the controller 20. The reference voltage generator 14 receives the battery voltage VBB and generates a reference voltage Vref. The voltage divider 16 generates a voltage (Vsen=(R2×VBB)/(R1+R2)) divided by the resistors R1 and R2. The comparator 18 receives the battery voltage VBB, compares the divided voltage Vsen with the reference voltage Vref, and generates a comparison output signal Vcom. For example, when the divided voltage Vsen is higher than the reference voltage Vref, the comparator 18 generates a high-level comparison output signal Vcom, and when the divided voltage Vsen is lower than the reference voltage Vref, the comparator 18 generates a low-level comparison output signal Vcom. The controller 20 detects the level of the comparison output signal Vcom and generates a sound for warning a user to change the battery 10 or displays a sign to change the battery 10 on a display unit (not shown). For example, when the low-level comparison output signal Vcom is generated, the controller 20 enables the user to recognize a need to change the battery 10.
That is, in the above-described apparatus using the battery, the battery voltage sensor senses the battery voltage VBB and informs the user of the time for the change of the battery 10. However, when the battery 10 is replaced by a battery having a low intrinsic voltage, even if high power remains in the replaced battery, the battery voltage sensor senses that a voltage of the battery is lower than the reference voltage Vref, and warns the user to change the battery.
For example, some batteries have an intrinsic voltage of 1.5V, while other batteries have an intrinsic voltage of 1.2V. Assuming that the battery voltage sensor is designed based on a battery having an intrinsic voltage of 1.5V such that the reference voltage Vref is 1.2V, when a battery runs down and is replaced by a new battery having an intrinsic voltage of 1.2V, even if high power remains in the new battery, the battery voltage sensor senses that the voltage of the new battery is lower than the reference voltage Vref and warns the user to change the battery.
Therefore, since a battery voltage sensor of a conventional apparatus using a battery senses a battery voltage and informs a user of the time to change a battery irrespective of the intrinsic voltage of the battery, the time to change the battery cannot be accurately detected.